Many thanks for the suggestion! I've started trying it out, and though it doesn't seem to work perfectly for fimfiction.net (half the .mobi files I create from fanfics there get rejected for some reason when I email them to my kindle), it so far seems to work fine with fanfiction.net at least.

An excuse for me to learn Python so I can fix whatever it's doing wrong. :-)

EDIT: On second thought, fimfiction.net allows me to get html downloads of the stories, which I can then email to kindle anyway -- so as long as fanficdownloader works with fanfiction.net, I'm all set :-) Thanks again.